/// <summary>

         /// 生成缩略图

         /// </summary>

         /// <param name="originalImagePath">源图路径（物理路径）</param>

         /// <param name="thumbnailPath">缩略图路径（物理路径）</param>

         /// <param name="width">缩略图宽度</param>

         /// <param name="height">缩略图高度</param> 

         public void CreateMinImage(string originalImagePath, string thumbnailPath, int width, int height)

         {

             System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));

             int towidth = width;

             int toheight = height;

             int ow = originalImage.Width;

             int oh = originalImage.Height;

             //新建一个bmp图片

             System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

             //新建一个画板

             System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

             //设置高质量插值法

             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

             //设置高质量,低速度呈现平滑程度

             g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

             //清空画布并以透明背景色填充

             g.Clear(System.Drawing.Color.Transparent);

             //在指定位置并且按指定大小绘制原图片的指定部分

             g.DrawImage(originalImage, new System.Drawing.Rectangle(, , towidth, toheight));

             try

             {

                 //以jpg格式保存缩略图

                 string FileExt = Path.GetFileNameWithoutExtension(originalImagePath);

 //这里报错               bitmap.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);

             }

             catch (System.Exception e)

             {

                 throw e;

             }

             finally

             {

                 originalImage.Dispose();

                 bitmap.Dispose();

                 g.Dispose();

             }

         }

 //修改后的代码

 public void CreateMinImageAndDel(string originalImagePath, string thumbnailPath, int width, int height)

         {

             Graphics draw = null;

             string FileExt = "";

             System.Drawing.Image originalImage = System.Drawing.Image.FromFile(HttpContext.Current.Server.MapPath(originalImagePath));

             int towidth = width;

             int toheight = height;

             int ow = originalImage.Width;

             int oh = originalImage.Height;

             //新建一个bmp图片

             System.Drawing.Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

             System.Drawing.Image bitmap2 = new System.Drawing.Bitmap(towidth, toheight);

             //新建一个画板

             System.Drawing.Graphics g = System.Drawing.Graphics.FromImage(bitmap);

             //设置高质量插值法

             g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

             //设置高质量,低速度呈现平滑程度

             g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

             //清空画布并以透明背景色填充

             g.Clear(System.Drawing.Color.Transparent);

             //在指定位置并且按指定大小绘制原图片的指定部分

             g.DrawImage(originalImage, new System.Drawing.Rectangle(, , towidth, toheight));

             try

             {

                 //以jpg格式保存缩略图

                 FileExt = Path.GetFileNameWithoutExtension(originalImagePath);

 　　　　　　　　　　//用新建立的image对象拷贝bitmap对象 让g对象可以释放资源

                 draw = Graphics.FromImage(bitmap2);

                 draw.DrawImage(bitmap, , );

             }

             catch (System.Exception e)

             {

                 throw e;

             }

             finally

             {

                 originalImage.Dispose();

                 bitmap.Dispose();

                 g.Dispose();

 　　　　　　　　　　//保存调整在这里即可

                 bitmap2.Save(HttpContext.Current.Server.MapPath(thumbnailPath) + FileExt + ".jpg", System.Drawing.Imaging.ImageFormat.Jpeg);

             }

         }